Fuel feed system



Aug 18, 1953 Filed Nov. 12. 1946 3 Sheets$heet 1 I 7 iii; I 4

l 4' I 37 I\ 1 I l gi I 59- 50 2/ 35 26 22 27 33 24 5 35 36 INVENTOR 12 ""lllllllllrlllllllll 8- 8, 1953 G. R. ERICSON 2,649,051

FUEL FEED SYSTEM Filed NOV. 12, 1946 3 Sheets-Sheet 2 i 64 9A 4 4a I I 554 II F l G. 3

INVENTOR Aug. 18, 1953 G. R. ERICSON FUEL FEED SYSTEM Filed Nov. 12, 1946 3 Sheets-Sheet 3 r 35 W W l G INVENTOR Patented Aug. 18, 1953 FUEL FEED SYSTEM George R. Ericson, Kirkwood, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporationof Delaware Application November 12, 1946, Serial No. 709,123

9 Claims. (01. 103-113) This invention relates to fuel supply systems for internal combustion engines, and has particular reference to novel and effective means for selectively permitting the escape under low pressure of gases and vapors from the fuel pump, Without releasing substantial quantities of fuel from the supply system, so that the pump will not become locked" with vapors.

As will appear hereinafter, the present invention is especially suitable for application to a fuel supply system of a character commonly employed upon aircraft and in automotive practice, wherein fuel such as gasoline, is stored in an atmospherically vented tank. In such systems the stored fuel is withdrawn and delivered through a supply line leading to the engine, under a desirable degree of pressure feed as may be established by a pump, the latter usually being located at the tank end of the supply line.

It is Well known that when a supply system of this character is subjected to relatively low atmospheric pressure, as, for example, in high altitude operation of aircraft, or to unusually high atmospheric and ambient temperatures, air and the low boiling constituents normally in solution in the liquid fuel, evolve as a mass of bubbles throughout the body of fuel in the tank and particularly, when agitated by the pump. Such gas and vapor bubbles collect in the pump, and due to their lack of viscosity and weight, sharply reduce the pressures which can be developed in the pump, particularly if it is of the valveless or centrifugal type. This is the condition which is known in the art as vapor lock. Accordingly, it is the principal object of the present invention to provide means in a supply system of the character indicated, for disposing of the bubbles in such a way that they will not substantially interfere with or materially af-' feet the pressure or volume of the flow of liquid fuel to the engine.

It is another object of the invention to provide means for instantly increasing the speed of a centrifugal pump, and the volume delivered thereby, when the pumping chamber becomes filled with vapor as distinguished from liquid to such an extent as to interfere with the development of the pressure of liquid fuel which is desired.

It is a further object of the invention to provide a selective means for releasing bubbles from the pump in such a manner that they cannot collect and accumulate sufliciently to substantially interfere with the action of the pump to 2 deliver the desired volume of liquid fuel at the desired pressure.

It is a further object of the invention to provide a fuel pump having the above described advantages, and also being constructed and arranged to prevent the accumulation of water in the pump chamber when the pump is standing idle, which might freeze and prevent the pump from operating.

Additional objects and advantages will appear readily from the following description of preferred embodiments of the invention as such are shown in the accompanying drawings, wherein:

Fig. 1 illustrates in fragmentary vertical section, a fuel storage tank having therein a fuel feed pump assembly shown partly in vertical section, wherein is incorporated improvements afforded by the present invention, the view in respect to the pump assembly, being taken along the line |--l in Fig. 2;

Fig. 2 is a horizontal section through the pump assembly, illustrating certain features of the invention;

Fig. 3 is an elevational view partly in vertical section, of a pump assembly showing a modified form of the invention;

Fig. 4 is a view similar to that of Fig. -3, but illustrating a further modified form of the invention;

Fig. 5 is a detail view showing a slightly modified form of a vent control valve.

With reference first to the embodiment of the invention as appears in Figs. 1 and 2, a fuel delivery pump which is here designated generally by the numeral H), is arranged according to present example, in a lower zone of the fuel storage tank I l, the pump being suitably mounted above the tank sump l2 as by a bracket 9. Pump H! preferably is of an electric motor driven centrifugal type, and includes a motor casing l3 housing a suitable electric motor shown only in part, as the vertical depending pump drive shaft 14 thereof, the armature commutator assembly l5 and one of the commutator brushes H5. Carried at the lower end of easing I3 is the pump casing or volute ll formed by preference in two parts I 8 and I9 secured together and to casing I3 by bolts 2! The casing parts wand 89 cooperate to define a pump impeller chamber 2!, within which rotates the impeller 22. Thecentral pump intake opening or throat 23 is provided in the casing part I8, opening below the impeller axial portion to the tank sump 12 as shown. A suitable screen 24 may 3 be provided across the intake throat to prevent passage of foreign solid matter or dirt into the pump.

In a system of the character here afforded, as for the handling and feeding of liquid fuel such as gasoline, the sump I2 provides a zone of sediment collection as well as a low point in the tank for the collection of such water that may be contained in the stored fuel. Removal of water and sediment from the tank is thus facilitated, as by periodically opening a sump drain through removal of the drain plug 25. In this connection, it is of advantage to locate the pump assembly H! such that the intake throat 23 is directly exposed to and overlies the sump, so that whatever water may be in the fuel flooding the volute chamber at times when the pump is inactive, may separate out through intake throat and collect in the sump. As a means for facilitating such water separation, the volute chamber 21 is given a relatively shallow dished shape in transverse section, downwardly toward the intake throat 23, while the impeller 22 1s shaped correspondingly, such that the impeller disc 23 is dished as shown, and the impeller blades 27 mounted on the under side of the disc, extend at an inclination upwardly from the zone of the throat 23. The top wall of the volute chamber at its periphery spirals upwardly from the point A (Fig. 2) to the adjacent point 34 where the volute merges with delivery passage 35.

The impeller hub 28 extends upwardly through an opening 29 in pump casing part 19 for suitable operative connection with motor shaft I4, and as here preferred, the impeller is operatively supported in part, by a step bearing comprising a ball element 3!} recessed in the lower end of the hub and engaging a fixed bearing step 3| in the zone of the intake throat 23. It is preferred, also, to provide the impeller disc with one or more ports 32 therein near the hub, for permitting such water as may tend to collect in the space 33 over the pump casing part Hi, to pass or drain through the hub clearance space in opening 28 and through the ports 32 to the pump chamber, from whence the water may settle through the intake throat into the tank sump when the pump is inactive.

The foregoin provisions for water drainage from the space 33 and from the pump chamber 2! serve to prevent water accumulation and possible icing in these zones, should the tank assembly be exposed to cold or freezing weather for any appreciable length of time while the pump is idle.

The discharge side 34, (Fig. 2) of pump chamber 21 communicates with inclined delivery passage 35 here formed by cooperating extensions 35 and 3'! of the pump casing parts 18 and I9, respectively, extending therefrom and within the tank ll. Passage 35 extends upwardly and outwardly in substantial continuation of the inclination of the top wall of the volute periphery as previousl mentioned and terminates in upwardly directed end portion 38.

Portion 38 communicates with a flexible conduit as leading therefrom upwardly in the tank, for connection with a nipple 38, the latter preferably supported by a removable tank closure plate at at the top of the tank H. The nipple 40 affords a coupling between the conduit 39 and a delivery conduit (not shown) providing the fuel supply line to the engine. Further, and by present preference, a calibrated opening or relief port is provided at a suitable elevated point in the fuel supply line, as at 32 in the nipple 4, as a means for relieving any suction or sub-atmospheric condition in the line upon stoppage of the engine, which otherwise would tend to produce a syphoning of fuel from the tank since the latter is vented to atmosphere through a suitable tank vent port 43 (Fig. 1).

As hereinbefore indicated, when a fuel supply system of the character described above is subjected to a rarefied atmosphere or to high atmospheric and ambient temperatures, a condition of liquid fuel boiling usually results. In such instances, air and other gases which otherwise normally remain in solution in the liquid fuel, evolve as a mass of bubbles in the fuel, while the lighter fuel constituents tend to form vapor bubbles therein. Such gas and vapor bubbles, if permitted to remain in the fuel, may adversely affect pump operating efficiency and frequently cause so-called vapor lock. According to the present invention, the gas and vapor bubbles are directed upwardly through the pumping spaces to the removal device now to be described and i embodied in or made a part of the pump as sembly H1 in tank I I.

The pump casing extensions 36 and 31 are so formed as to provide the portion 44 of discharge passage 35, substantially in the form of a relatively shallow horizontal chamber preferably of cylindrical shape. Chamber 44 is open on its upper side as provided by an opening 55 in the extension 37, for communication with a vertically directed preferably cylindrical closure 46 provided by casing 57, the lower open end 48 of the latter chamber being in overlying registry with opening 45. Casing 4'! is flanged at 49 to afford mounting securement thereof on the extension 3?, as may be effected by certain of the bolts 50 serving to secure the extensions 35 and 3'! in assembly. In the present example, the diameters of the passage chamber c4, chamber 46 at least at its lower open end 48, and the opening 45, are substantially coextensive so as to afford un- 1 restricted communication of the chambers.

When the fuel tank H is substantially full or at least filled to an extent such that the separator casing 41 is submerged in the fuel pond, the casing chamber 46 normally will be flooded through its communication with the fuel pond by way of the pump chamber and pump discharge passage 35. Now upon operation of the pump, a circulation or pressure-flow of fuel will occur from the pump discharge to and through the passage 35 (including chamber 4%), conduit 39 and the delivery line leading therefrom to the engine. Since the chamber 46 is in full communication at its lower end, with the chamber portion 4 of passage 35, pressure-circulation of fuel will take place in and through chamber 46, from which it will appear that the latter chamber is in effect, a part of the delivery line from the pump. As fuel circulation occurs in chamber 46, gas and vapor bubbles which may be contained in the fuel, will rise therein and collect or accumulate in the upper or cap zone 5| of the chamber. Cap zone 5! is of substantially conical shape, to permit free flow of air or vapor toward its apex. Thus the chamber 46 constitutes the bubble separation portion of the pump assembly. Since the fuel spaces within the pump, or, at least, the upper walls thereof, slope continuously upwardly and merge in the sloping discharge passage 35, bubbles formed anywhere in pump or connections will tend to rise and be directed into the vapor separator.

Removal or venting of the gases and vapors collecting in the chamber zone 5!, is afforded according to the embodiment of Fig. 1, by an upwardly directed vent passage 52 formed in the cap 53 of casing 41, the passage communicating with a vent conduit 54 leading therefrom upwardly in the tank I I and terminating in an open end 55 disposed near the top of the tank such as to be above the normal full tank fuel level. In order to prevent any substantial fuel by-pass return to the tank through the vent, a float valve 56 is arranged in chamber 46 in control of the vent passage 52. The valve comprises a float element 5'! suitably fixed to a vertical spindle 5B, the lower end of the latter being guided in a recess 59 formed in the pump casing extension 36, and the upper end thereof being loosely guided in a cap recess 60 and adapted at 6| for cooperation with the vent passage 52 as a control valve therefor. Cap recess 50 communicates with cap zone 5! at the apex of the latter, so that the free upward movement of vapor from chamber 46 into vent passage 52 is unimpeded. When the chamber 46 is filled with fuel, the float 5! will rise, due to the pressure exerted by the liquid, to position the spindle end Si in closing relation to the vent passage 52, thus permitting in zone 5|, accumulation of gases and vapors issuing from the fuel circulating through the chamber. Now as the gas pressure in space 5i increases, the liquid level in 46 lowers and the float thereby will be displaced downwardly in chamber 45 sufficiently to unseat the valve end El, and release the accumulated gases and vapors. Thereupon the float will again rise to reclose the vent passage. Opening of the vent thus occurs periodically or intermittently, in response to pressure of accumulated gases in space 5!. The operation of the gas and vapor bubble separator and removal provision according to the embodiment of Figs. 1 and 2, is now believed to be fully apparent from the foregoing description. It may be noted however, that whenever the pumping spaces become charged with vapor, the resistance to rotation of the impeller is decreased, and, the motor being series wound, its speed and capacity are greatly increased, thus, through the tendency of the bubbles to rise and the increased pumping action the vapor is quickly eliminated through the vent, and substantially bubble-free liquid fuel will then remain in the chamber for delivery to the engine.

The pump and bubble separator assembly according to the embodiment of Fig. 3, is similar to that of Fig. 1, so that corresponding parts shown in Fig. 3 are given the same reference numerals as are applied to Fig. 1, differentiated however, by the letter suflix A. The modification here resides in adding a constantly open port ll] of predetermined small capacity, in a side Wall of the separator chamber casing 41A and preferably near the lower end of the latter, this port affording a highly selective bleed opening between chamber 46A and the tank.

In addition to port 16, a baffle H is provided in the passage chamber MA transversely to the line of fluid flow, to direct the fuel discharge operative support of the float valve 56A, provides a guide recess 12 therein to receive the lower end of the float spindle 58A. In this form, as well as in Figs. 4 and 5, the discharge passage from the pump is horizontal, the upward inclination of the pumping space and the fuel move ment being relied upon to direct bubbles through the passage to the separator.

Fig. 4 illustrates a further modified form of separation device which is effective substantially equally with the first described embodiments in respect to bubble removal, but which does not include float control of the vent. Some of the structural parts are similar to the corresponding elements of the device according to Fig. 1, and hence such parts may be designated by the same reference characters but diiferentiated by the letter suffix B.

In the modified form shown, a baffle 15 preferably formed as a part of the pump casing extension 36B, is arranged transversely to the line of fuel flow from the pump and projects an appreciable distance upwardly into the separator chamber 46B, as substantially to the extent shown. Ihe bafile thus serves in a positive manner, to constrain the fuel discharge from the pump to a line of flow upwardly in the separator chamber, thence over the baffle and downwardly in the chamber on the opposite side of the bafile, to and through passage 35B, conduit 39B and connected supply line leading to the engine. Gas and vapor bubbles are trapped in the chamber 353, as in the case of the first described embodiments, and collect in the upper zone 5IB of the chamber, from which they are vented through a vent port or passage 16 in the casing cap portion 533. Vent 16 in the instant modification, however, opens'directly to the body of fuel in the fuel tank.

Fig. 5 illustrates a modified form of separation device similar to Fig. 4, except that the vent is partially filled by the plug 80, which is provided with a tapered valve portion 81 at its lower end, and is normally held in closed or nearly closed position against the spring 82 by the pressure developed in the pump. When the pressure falls below normal, the valve is opened by the spring to permit increased escape of vapor. Practically no liquid fuel escapes because the presence of liquid at the top of the chamber implies a pump chamber substantially free from bubbles, and this condition would be followed by the development of fuel pump pressure, which would nearly close the valve 8|. Consequently, the vent and valve as provided, is such as to permit only a negligible degree of fuel by-pass return therethrough to the tank during pump operation, but yet such as will readily permit escape of gas and vapor bubbles.

While several presently preferred embodiments of the invention are herein shown and described, it is to be understood, of course, that such are intended as illustrative of the invention and not limiting, as all such modifications as come within the spirit and scope of the appended claims are contemplated.

I claim:

1. In a tank-mounted, submerged type pumping unit for volatile fuels, the combination in a pump of means for separating vapors and gases from the fuel by circulation of the fuel and for venting the vapors and gases separated to maintain pump efficiency and delivery pressures, comprising a body for said pump including an intake, a pump discharge port, an open circulating cham- 7" ber between said intake and said port for separation of vapors and gases from the pump, and a pump discharge passage leading from the pump intake to and through said chamber to the said port, a closure for said chamber to trap the vapors and gases separated, a vapor-gas vent in the closure, and means including a vent valve and a fluid actuated means for the valve in the chamber operative by the fluid delivered by the pump to control the vent.

2. In a tankrnounted, submerged type pumping unit for volatile fuels, the combination in a pump of means for separating vapors and gases from the fuel by circulation of the fuel and for venting the vapors and gases separated to maintain pump efiieiency and delivery pressures, comprising a pump body having an intake, a pump discharge port, an open circulating chamber between said intake and said port for separation of vapors and gases from the pump, and a pump discharge passage leading from the pump intake to and through said chamber to the said port, said passage being inclined with respect to the horizontal continuously upwardly and outwardly to the said chamber for escape of vapors and gases from the pump, a closure for said chamber to trap the vapors and gases separated, a vaporgas vent in the closure, and means including a vent valve and a fluid actuated means for the valve in the chamber operative by the fluid delivered by the pump to control the vent.

3. In a pumping unit for volatile fuels, the combination of a pump and means for separating vapors and ases from the fuel by circulating the fuel from the pump and for venting the vapors and gases separated to maintain pump efficiency and pressures, comprising a vertical pump having an upwardly dished rotor and a rotor casing, said rotor casing including an inlet portion facing downwardly of the rotor, an upwardly and outwardly inclined casing portion in the shape of a volute, a rotor casing extension containing an opensided circulating chamber, connected discharge passages in said extension and volute leading from the volute to and through said chamber to a discharge port, means registering with the open side of said chamber extending said chamber upwardly and forming a closure therefor to trap gases and vapors discharged by the pump separated in the circulating chamber and operative continuously during pump operation, a vent in the upper portion of said closure, valve means for controlling the vent, and means to actuate the valve to open and close the vent.

4. In the combination defined by claim 1; a second continuously open vent for said chamber.

5. In the combination defined in claim 1; said vent leading to the surface of the pond and said closure having a constantly open vent port.

6. In the combination defined by claim 1; means in said passage adjacent said chamber for deflecting the liquid flow in the direction of said closure.

7. In the combination defined by claim 1; means in said chamber constraining liquid flow thereto to circulation through said chamber.

8. The combination with a centrifugal pump submerged in a pond of liquid such as gasoline, of a casing for said pump having an extension, a discharge port in said extension, and a delivery conduit connecting the pump with the port and receiving liquid from the pump for delivery under pressure through the conduit to the port, of means for separating gases and vapors from the liquid in said conduit, comprising means forming an open chamber in said conduit for permitting circulation through the chamber of liquid under pu'mp'discharge pressure in the conduit, means registering with the open side of said chamber extending said chamber upwardly and forming a closure therefor to trap gases and vapors separated from the liquid while under pump pressure passing through the conduit and chamber during operation of said pump, a vent passage in said closure leading from the upper part or" said chamber to a zone above the surface of the pond, and a float valve in the chamber normally closing said vent passage upon liquid circulation through the chamber, said float valve responding to pressures of fluid in the chamber to open or close said vent passage.

9. A tank mounted fuel delivery device located adjacent the sump of the tank, comprising a motor driven horizontal impeller having a hub, an upwardly facing dished shroud integral with the hub, and blades on said shroud lower face, a pump casing including a volute portion and of internal contour complementary to the impeller having a central inlet opening on the underside thereof and tapering downwardly and inwardly toward said opening from said outer volute portion for draining water therethrough and for directing bubbles upwardly into the volute part of the casing, openings in the upper wall of said casing and in said shroud adjacent the hub for facilitating drainage of water downwardly from the upper surface of said casing to the up er surface of said shroud and thence off the shroud upper surface through said shroud to said inclined casing and the sump of said tank, a discharge fluid conduit from said casing, a discharge port for said conduit, and vapor venting means between said casing and said port in said conduit through which all of the fluid passes for separating bubbles from the fluid whiie the pump is delivering through said port.

GrECJRGE R. ERICSON.

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